When configuring a vehicle's suspension, the primary considerations for the automobile designer are the design goals set for passenger ride comfort and overall vehicle performance. In general the designer first selects the type of suspension required by the style of vehicle, i.e., high performance car, luxury sedan, compact economy car, SUV, etc., and then configures and adjusts the selected type of suspension to meet the specific design goals set for the vehicle.
Various suspension types exist, each of which provides specific driving characteristics. One common characteristic of each type of suspension, however, is the in-board mounting of the damper and spring assembly regardless of whether or not the damper and spring are coaxially mounted. This in-board mounting scheme is illustrated in the torsion beam rear wheel suspension system disclosed in U.S. Pat. No. 7,946,600. In this system one end of each arm of a pair of trailing arms is pivotally supported by the vehicle body via a rubber bush joint. The other end of each trailing arm extends outward and rearward and supports the corresponding rear wheel via a hub bearing unit. At intermediate locations, the two trailing arms are connected to, and separated by, a torsion beam. Located between the torsion beam coupling and the hub bearing unit of each trailing arm is a spring seat, thus providing means for resiliently supporting the trailing arm with a coil spring interposed between the spring seat and the vehicle body. A damper, located behind the coil spring, extends between the corresponding trailing arm and the vehicle body. A similar suspension configuration is disclosed for use with an in-wheel motor in U.S. Pat. No. 8,220,808.
A different type of suspension, typically referred to as a multi-link suspension, is disclosed in U.S. Pat. No. 6,938,908. In the disclosed suspension assembly each wheel support is connected to the vehicle body using five links. A coaxially arranged damper-coil spring assembly is interposed between the vehicle body and an inward projection of the wheel support. When viewed from the side, the damper-coil spring assembly extends in a substantially vertical direction while the assembly, when viewed from the rear, angles slightly inward towards the vehicle's centerline. A similar suspension configuration is disclosed in U.S. Pat. No. 5,507,510.
Yet another type of suspension, commonly referred to as a double wishbone suspension, is disclosed in U.S. Pat. No. 6,945,541. In this type of suspension the wheel mount is coupled to upper and lower control arms via ball joints, where each substantially horizontal control arm is approximately parallel to the road surface. A coaxial damper-spring assembly is interposed between the wheel mount and the vehicle body and positioned such that it is substantially vertical when viewed from the side, and angled inwards towards the vehicle's centerline when viewed from the rear.
Regardless of the type of suspension, in general the damper-spring assembly angles inwardly towards the vehicle's centerline when viewed from the rear of the car. The degree to which the assembly intrudes upon either the passenger compartment or the luggage compartment depends both on the angle of the assembly and the mounting location of the assembly to the wheel mount. The configuration of the assembly, for example whether or not the damper and spring are coaxially mounted and where the spring is mounted relative to the damper and wheel mount, also impacts the degree of interior space intrusion. Accordingly, what is needed is a damper-spring assembly that minimizes interior space intrusion while still achieving the desired level of ride comfort and vehicle performance. The present invention provides such a damper-spring assembly.